Machine-switching telephone-exchange system.



A. E.VLUNDELL.

MACHINE SWITCHING TELEPHONE EXCHANGE SYSTEM.

' APPLICATION FILED SEPT-27.19I5.

1,203,887. 7 PatentedNov. 7,1916.

In venfor: A/ken Lundg/Z' MM/Mu ALBEN E. LUNDELL, OF NEW YORK, N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, TO WESTERN ELECTRIC COMJPANY, INCORPORATED, A CORPORATION OF NEW YORK.

v To all whom it may concern Be it known that I, 'ALBEN E. LUNDELL, a citizen of the United States, residing at New York, in the county of Bronx and State of New York, have invented certain new and useful Improvements in Machine- Switching Telephone-Exchange Systems, of

which the following is a full, clear, concise,-

and exact description.

This invention relates to telephone eX- change systems employing machine switchlt is the practice to signal a wanted party 7 by intermittently ringing the bell at his substation. This is done automatically by a ringing machine at the connector, such machine having a commutator on the shaft or equivalent means for breaking the call up into short rings. It frequently happens that connection is made with a wanted line during what is known as a silent interval of the ringing machine; that is, while the open circuit part of the commutator is con-.

nected with the called partys line. This results in loss of time.

The object of this invention is to provide a circuit arrangement whereby ringing current is applied to the called line for a short interval immediately the connector is set thereon, and intermittently to apply current thereto if the called subscriber does not re- I spond to such preliminary signal.

In accordance with this invention two sources of ringing current are provided, one being the ordinary ringing machine adapted to ring intermittently the called partys bell, and the other a continuous source of' ringing current. The application of these sources of current to the called line \IS controlled by a relay. This relay is adapted to be connected in circuit with an interrupter.

-mature and front contact apply current to the called line from said ringing machine. The ringing machine and interrupter are so related that the ringing interval of the former begins before the interrupter brush passes onto a metallic segment of the com- Specification of Letters Patent.

Application filed September 27, 1915. Serial No. 52,880.

Patented Nov. 7, 1916.

mutator. Thus if, when the connector reaches the called line terminals, the said relay is energized, rmgmg current is instantly applied to such line from the ring- 7 derstood when described with reference to 1 the accompanying drawing, which illustrates only so much of a telephone exchange system as is necessary for a comprehension of the invention.

The calling substation A may be extended to a first selector, the brushes 10, 11 and 12 and terminals 13, 14 and 15 only of which are shown, by a line finder or equivalent means upon the removal of the receiver thereat. This selector may be of the powerdriven type and may be set upon the terminals13, 14, 15 of an idle trunk 16, 17, 59, by any well-known means, as shown, for example, in British Patent No. 21,260 of 1911. The springs 18, 19 designate sequence switch contacts of the first selector sequence switch, which contacts, during the control of the selectors and connector are closed to their bottom contacts to associate the operators sending equipments with such switches. During the setting operation of the connector, the sequence switch spring 26 wouldbe closed to its bottom contact to associate the sender with such connector.

hen the train of switches has established the connection to the desired line, the springs referred to would be closed to their top contacts to disconnect the sender and complete the talking circuit. hen the connector brushes 20, 21, 22 are set upon the terminals 28, 24, 25 of theselected line, a control relay (not shown) becomes denergized. This relay closes its back contact and advances the sequence switch ofthe connector to the 'next position, transferring its spring 26 to its upper contact. In such position, the sequence switch spring 27 is closed, resulting in the energization of relay 28 over the following circuit: free pole of battery, sequence switch spring 27, conducfor 30, relay 28, conductor 31, armature and back contact of relay 29, conductor 32, armacluding the transmitter 53 and primary to ground.

ture and back contact of relay 33 to ground. Relay 28 transfers its armatures to their inner contacts. This results in the closure of the following circuit to ring bell b at substation B: generator 34:, left armature and back contact 57 of relay 35, conductor 36, relay 33, conductor 37, armature 50 and front contact of relay 28, connector sequence switch contact 38 (now closed), brush 21, terminal 24, conductor 39, bell b, condenser quence switch contact ll' (now closed), armature 51 of relay 28 and its front contact The source of ringing current 34 is continuously closed to the back contact 57 of the left armature of relay 35, and

consequently when relay 28 becomes ener' gizedas the connector reaches the called line, the bell Z) is instantly rung. An interval of say ten seconds may now elapse before brush *2 of interrupter 43 rides onto a metallic segment ll of such interrupter. If the subscriber at substation B removes his receiver 52 from its switchhook during this interval, the increase in the strength of the ringing current, dueto the closure of the shunt about the hell b and' condenser c in- 54 of the induction coil, causes the relay 33, which is marginal, to become energized in the well-known ma'nner.- This relay in attracting its armature opens a shunt about tor over sequence switch contacts 41 and 38. If the called party does not respond during this interval, when the brush 42 of interrupter 43 next engagesv a metallicsegment 4% of the commutator, the; followmg circuit is closed to energize relay 35:

free pole of battery, metallic segment i l,

brush l2, conductor 45, spring 46 of relay35 and its back contact, relay 35, conductor 4:7,

armature l8 of relay/28 and its front con-,

tact to ground. Relay. 35 by attracting its right armature, locks itself to ground at the armature l8 and front contact of relay 28 independent of the interrupter 4:3. By attracting its left armature, it opens the ringing circuit just traced from the generator 34: and closes the following ringing circuit from generator 49: free pole of battery, generator 4:9, interrupter 60, left armature and frontcontact 58 of relay 35,.conduct'or 36,

relay armature 50 and front contact ofv relay 28, sequence s'witch contact 38, brush 21, term1nal'24, conductor 39, hell 6, condenser a, conductor 40, terminal 23, brush 20, sequence switch contact 41, armature'51 and front contact of relay.28 to ground. The hell I) at substation B will now be inconductor 40, terminal 23, brush 20, se-

interrupter -l3 is in contact with the metallic segment A of the commutator, the brush 61 of interrupter 60'is also riding over a metallic segment 62 of such interrupter, in order that current may be immediately applied to the called line.

In order to permit trip relay 33 to cut off the ringing current during the silent interval of the ringing machine, tripping battery may be connected to a metal segment on the shaft of interrupter 60 in a manner Well known in the art. I Talking current is fed to the calling party from battery 63 and to the called pa "ty from battery 64 in the well-known'manner.

The release of the switches may take place by the depression of a key by the operator, as shown in detail in the patent mentioned.

\Vhat is claimed is:

1. In a telephone exchange system, the combination with telephone lines, a connector wherein said lines terminate, and means for settin said connector on said lines, of a relay, a source'of current and aninterrupter for operating the same, two sources of ringing current controlled by said relay, electromagnetic means adapted to operate when the connector is'set on the called line and to connect one or the other source in circuit with the called line dependent upon the condition of said relay, and means forcutting off the ringing current when the called party on the called line to connect oneor the other of said ringing current sourcesto the called line dependent upon the condition-of said relay, and means for cutting off! the ringing current when the called party'answers.

3. In a telephone exchange system, the

combination with telephoneglines, a connector wherein said lines terminate, and means for setting said connector on said lines, a relay, a source of continuous ringing cur-' rent connected to the back contact f said relay, a'source of interrupted ringi; current connected to the front contact of said relay, a source of current and an interrupter thereto to the called line, and. means for cutting off the ringing current when the Called 10 party answers.

In witness whereof I hereunto subscribe my name this 25th day of September, A. D. 1915.

ALBEN E. LUN DELL. 

